Predetermined torque release wrench



Nov. 17, 1959 J. J. coRNwELl. 2,912,889

PREDETERMINED ToRQUE RELEASE WRENCH Filed Feb. 5, 1958 -4 sheets-sheet 1 United States Patent() PREDETERMINED TORQUE RELEASE WRENCH John I. Cornwell, Whittier, Calif., assignor to George C.

' Jenkins, San Gabriel, Calif.

Application February 5, 1958, Serial No. 713,380

11 Claims. (Cl. 81-52.4)

- efficient wrench of this type and is particularly directed to a problem that is inherent in the use of radial driving pressure. The problem arises because a circumferential series of successive driving faces is provided to permit the desired yielding driving action to occur at various rotary positions of the rotary driving member. The rotary driving member that receives the radial driving pressure may be of flat cross-sectional configuration to provide driving action at two diametrically opposite rotary positions; or the driving member may be of square crosssectional configuration for driving action at four equally spaced rotary positions; or the driving member may be hexagonal to provide six driving faces for use at six equally spaced rotary positions of the wrench; or the driving member may even be octagonal in cross-sectional configuration to provide eight driving positions.

When the torque load rises to a magnitude suicient to overcome the radial driving pressure, the driving pressure is shifted from one peripheral driving face to the next driving face. The driving pressure may be exerted, for example, by a pressure member in the form of a radially positioned plunger that is urged towards the driving member by a suitable spring. When the torque load exceeds the force exerted by the spring, the plunger retracts against the resistance of the spring to permit a new face to rotate into contact with the plunger. The problem resides in the fact that this shift from one face to another has a reverse rotational effect on the second driving face. The two successive faces form a peripheral shoulder which slides past the plunger in the transition to the second face and as soon as the plunger rides over this shoulder, it presses in the reverse direction against the shoulder to tend to reverse the rotation sufliciently for abutment of the plunger flat against the second face.

With a flat two-sided rotary driving member, the tendency for reverse rotation extends through a rotary angle of approximately 90 degrees; with a square driving member providing four driving faces the tendency for reverse rotation extends through an angle of approximately 45 degrees; with a hexagonal driving member the tendency for reverse rotation extends approximately 30 degrees; and with an octagonal driving member providing eight driving faces the tendency for reverse rotation extends over an angle of 221/2 degrees. Thus, where the driving member has N number of driving faces at equal angular spacing, the range of the reverse rotational eect is ap proximately through an angle of 2,912,889 'Patented Nov. 17, 1959 ICC The purpose of a torque wrench of this type is to tighten nuts and the like to a predetermined torque with the spring accurately adjusted to yield at this particular torque. If, however, the tightened nut is immediately subjected to the described reverse rotational effect, this purpose is defeated. Moreover, the magnitude of the reverse rotational effect varies with the manner in which the wrench is manipulated. If the operator manipulates the wrench abruptly, the reverse rotational effect is less than when the wrench is manipulated with relatively slow swinging movement.

The invention meets this problem by providing a lostmotion connection between the multiple face driving member and the work-engaging member, the rotational range of the lost motion at least approximating the rotational range of the reverse rotational effect. The range of lost motion is preferably not substantially less than and not substantially more than The preferred embodiment of the invention provides a ratchet connection between the multiple faced driving member and the work-engaging member so that manual oscillation of the wrench produces uni-directional rotation of the work engaging member. The two members are coaxial and a simple spring-pressed crown ratchet connection is used. A second work-engaging member is provided for opposite nut-loosening driving force, and for this purpose is driven by a crown ratchet that is lixedly mounted in the wrench body. The virtue of this arrangement of two work-engaging members is the simplicity of the structure and the durability of the two driving mechanisms, since simple ratchets may be used without the disadvantages and complications of a reversible ratchet. The various features and advantages of the invention may be understood by reference to the following detailed description, considered with the accompanying drawings; In the drawings, which are to be regarded as merely illustrative: Figure 1 is a view of the presently preferred embodiment of the invention, the view being largely in cross- Section and partly in side elevation;

Figure 2 is a plan view of the same embodiment;

Figure 3 is an enlarged cross-section taken as indicated by the line 3-3 of Figure 1 and showing the driving plunger in abutment against a driving face of a hub member that is square in cross-sectional configuration;

Figure 4 is a side elevation of the driving mechanism employed in this first embodiment of the invention.

Figure 5 is a cross-section on an enlarged scale taken as indicated by the line 5 5 of Figure 4 and showing the relative positions of the hub member, the surrounding multiple faced driving collar and the driving plunger when the wrench is in operation against a torque load of less than the predetermined magnitude;

Figure 5a is a view similar to Figure 5 showing how the spring-pressed driving plunger climbs a shoulder be-v tween two of the driving faces of the driving collar when the predetermined torque load is reached;

Figure 5b shows the reverse rotation that occurs when the spring-pressed driving plunger exerts force on the of hub member for the various embodiments of the invention;

Figure 7f is a view similarto Figure 4 showing the driving mechanism of a second embodiment ofl the invention which employs a hexagonal driving collar;

Figure 8 is an enlarged cross section taken as indicated by` theline 8 8 of Figure 7 showing the relative positions of the-hub member, the surrounding hexagonal driving-collar and-the driving plunger in the course of a, nuttightening operation before the predetermined torque load is reached;

Figure 8a is a View similar to Figure 8 showing the driving plunger climbing a shoulder of the driving collar when thepredetermined torque loading is reached;

Figure 8b isa similar view showing the reverse rotation-of the driving collar that occurs as tne driving plunger rides over the center of the shoulder;

Figure: 94 is a view similar to Figure 4 showing a driving'` mechanism of a third embodiment of the invention that'incorporates an octagonal driving collar;

Figure 10y is an enlarged section taken as indicated by the line 10-10 of Figure 9 showing the relative positions of the hubmember, the surrounding driving collar and the driving plunger when the wrench is operated against a torque load that is less than the predetermined maximum;

Figure 10a is a similar view showing the driving plunger climbing a shoulder of the driving collar after the predetermined torque loading has been reached; and

Figure 10b is a similar view showing the reverse rotation of the hub collar that occurs when the driving plunger climbs over the shoulder to exert pressure for bringing the next face of the driving collar into abutment with the end of the plunger.

In the first form of the invention, shown in Figures 1 to 6, the working parts are mounted in a hollow wrench body, generally designated by numeral 10, providing a handle or shank 10a and two working heads 10b and 10c at opposite ends of the shank. The head 10b houses drive mechanism for tightening nuts and the like having right hand threads and the head 10c houses driving mecha, nism to loosen the nuts. The shank 10a is of tubular configuration providing a longitudinal bore 12 and the head 10b has a cylindrical cavity 14 of stepped configuration in radial communication with the bore. The second head 10c has a cylindrical cavity 1S of stepped conguration that terminates short of the longitudinal bore v12.

The essential working parts associated with the nuttightening head 10b include: a work-engaging member generally designated by numeral 16; a hub member, generally designated 18, that is best shown in Figure 6; a multiple-face driving member or collar 20 that surrounds the hub member; a pressure member in the form of a driving plunger 22 that normally presses against one of the faces of the driving collar 20; and a heavy coil spring 24 that continuously urges the driving plunger against the driving collar.

The driving plunger 22 is slidingly mounted in a reduced portion 12a of the longitudinal bore 12 and is formed with an end enlargement 2S for relatively snug iit in the bore 12. The coil spring 24 is in compression between the driving plunger 22 and a spacer sleeve 26. The spacer sleeve abuts a sc rew threaded plug 28 at the outer end of the longitudinal bore 12. The screw threaded plug 28 may be rotatably adjusted to vary the compression of the spring 24 and for this purpose has a diametrical slot 30 across its outer face for engagement by a screw driver. The outer end of the longitudinal bore 12 may be iilled with a low melting alloy 32 to cover the plug and the diametrical slot to discourage tampering after the plug is adjusted for application of a predetermined maximum driving torque to the work-engaging member 16.

The work-engaging member 16 has an axial extension 34 at its outer end of square cross-sectional configuration for a releasable engagement with conventional socket members. For this purpose the axial extension 34 is provided in a well known manner with a spring-pressed de- 4i tent ball 35. The inner end of the work-engaging member 16 is enlarged to form a crown ratchet 36 havinga circular series of ratchet teeth 38, the teeth being inclined for right hand rotation.

As may be seen in Figures 1 and 6, one end of the hub member 18 is enlarged to form a second crown ratchet 40 having inclined teeth 42 for normal engagement with the teeth 38 of the work-engaging member 16. The opposite end of the hub member 18 forms a journal 44Y of reduced diameter. As shown in Figure l the journal 44 is embraced by a needle bearing 45 and abuts a small ball 46 which seats in` a socket 48. at the inner end of the cavity 14. The ball 46 is` on the axis of rotation ofl the hub member and serves as a thrust bearing to receiveaxial forces.

The two 4crown ratchets 36 and 40 are of matching cylindrical configuration and are journaled in a common needle bearing 50. It is apparent that the two needle bearings 4S, and 50 fix the axis of rotation of the assembly comprising the work-engaging member- 16, the. hub member 18 and the driving collar 20. The work-engaging member 16 is movable along its axis relative tothe wrench body for the required ratching cooperation with the hub member 18` and is continuously urged inward toward the, hub member by a suitable helical spring 52. The spring. 52 seats against a screw threaded bushing 54 which has an inner cylindrical portion 55, for holding the needle. bearing 50,in its assembled position. The bushing54 may, have a diametrical slot 56 on its outer face whereby. the. bushing may be tightened or loosened byy a suitable Spanner.

In this iirst embodiment of the invention, theperipheral configuration of the driving collar 20 is square, as shown diagrammatically in Figure 3, the driving collar havingl four tlat side faces 58a, 58h, 58a and 58d for cooperation with the driving plunger 22. In thev normal operation of rthe wrench for tightening a nutor the like the tubular. shank 10a serves as a handle for; manual turning movement of the wrench body about the axis of rotation of the Work-engaging member 16. The swinging movement of the wrench body in the driving direction is transmitted by the hub member 18 to the work-engaging member 16 through the ratchet teeth for` tightening action on the nut and on the reverse swinging movement of the wrench theV hub member 18y rotates in the reverse direction without imparting rotation to the work-engaging member.

When a nut that is being driven is tightened to the predetermined degree determined by the force exerted by the heavy coil spring 24, the driving plunger 22 retracts suiiiciently to permit the wrench to be turned without imparting rotation to the driving collar 20. Thel four side faces Stia-58d form four corresponding peripheral shoulders 60 and the driving plunger 22 retracts suiiiciently to ride over Whichever shoulder is in its path of relative movement. l the position of the plunger 22 and the driving collar 20 at the mid-point in the transition of the driving plunger. from one of the driving faces of the driving collar to the next succeeding driving face. It is apparent that only. slightly further lateral movement of the driving plunger 22 beyond this mid-point results in the driving plunger exerting force on the shoulder 60 in a reverse direction to tend to cause the driving collar to rotate backwards to a position placing the next successive driving face in abut-` ment against the end of the driving plunger. It is apparent that with a four-sided driving collar 20 the tendency is for the driving collar to rotate backwards approximately 45 degrees. Actually, the extent is slightly less than 45 degrees because the plunger must move slightly past center with respect to a shoulder 60 to create the reverse force.

In accord with the invention the operative connection between the driving collar 20 and the hub member 18 provides a range of lost motion which is at least approxi mately 45 degrees to keep the tendency for reverse rotation on the part of the driving collar from being trans- The dotted lines in Figure 3 show,

. mitted to the hub member. For this purpose the intermediate portion of the hub member 18 that is embraced by the driving collar 20 is of non-circular configuration and the interior of the drive collar is also of non-circular configuration to provide the required lost motion.

In the construction shown the hub member 18 is formed with an intermediate portion of non-circular configuration providing two parallel at faces 62, the hub member being relatively thin with respect to the spacing of the two fiat faces. Preferably, the other two faces 64 of this portion of the hub member 18 are of cylindrical curvature, the cylindrical curvature being concentric relative to the axis of rotation ofthe hub member.

The interior of the drive collar 20 is formed with two diametrically opposite cylindrically curved walls 68 that rotatably engage the curved side faces 64 of the hub member 18 to keep the drive collar positioned coaxially of the hub member. The interior of the drive collar 20 is further formed with two diametrically opposite inwardly projecting abutments 70 which present two corresponding shoulder surfaces 72 for driving pressure against the two side faces 62 of the hub member. The dimensioning of the hub member 18 and the drive collar 20 are such that the interior of the drive collar permits reverse rotation of the drive collar of at least approximately 45 degrees so that such reverse rotation of the drive collar may occur without being imparted to the hub member. Thus the drive collar 20 as seen in Figure 5 is freely rotatable relative to the hub member for approximately 45 degrees in the reverse or counterclockwise direction.

The operation` of the` wrench may be readily understood. Figure 5 shows thenormal position of the driving plunger 22 in abutment with a face 58a of the driving collar 20 forclockwise rotation of the driving collar to tighten a nut or the like. The tightening action is accomplished by oscillating the wrench body about the axis of the hub member 18 to cause the two crown ratchets 36 and 40 to cooperate for intermittent clockwise rotation of the work-engaging member 16.

When the nut is tightened to the desired degree that is determined by the force exerted by the spring 24, the clockwise movement of the wrench body results in the driving plunger 22 being retracted against the pressure of the spring as the driving plunger climbs a shoulder 60 of the driving collar 20. Thus Figure 5a shows how the driving plunger 22 shifts from abutment against the driving collar face 58a to climb the shoulder 60 between the driving face 58a and the next driving face 58b. It will be noted that the abutment surfaces 72 stay in contact with the fiat sides 62 of the hub member 18 during this retraction of the driving plunger 22.

As soon as the driving plunger moves past center with respect to the shoulder 60 its pressure against the shoulder creates a moment for reverse rotation and the driving collar 20 rotates counter clockwise from the position shown in Figure 5a to the position shown in Figure 5b where the driving plunger 22 abuts the next driving face 58b of the driving collar. It is apparent that this freedom for reverse rotation on the part of the driving collar 20 relative to the hub 18 prevents any reverse rotation effect. from being transmitted to the hub member for loosening action on the nut that has been tightened.

The secondvwrench head 10c for loosening nuts and the like having right hand threads is provided with a crown ratchet 74that is fixedly mounted in the inner end of the cavity 15. In the particular construction shown, the crown ratchet 74 has a serrated rim 75 and is driven into the cavitywith a forced fit. The crown ratchet 74 has ratchet teeth 76 inclined to impart counter-clockwise rotation to a work-engaging member 78.

i The work-engaging member 78 is formed with a crown ratchet 80 on its inner end having teeth 82 for engagement with the fixed crown ratchet 74... Vv-A-suitable spring 84 acts in compression between the crown ratchet 80 and a screw threaded bushing 85 to urge the work-engaging body 10 about the axis of the work-engaging member 78 for ratchet action to rotate the work-engaging member intermittently in the counter-clockwise direction.

Figures 7 to 8b indicate how the invention maybe modified by substituting a driving collar of hexagonal peripheral configuration for the square driving collar 20, the configuration of the hub member 18 remaining substantially the same. Since the driving collar 90 has six driving faces, the angular spacing of the faces is 60 degrees and the amount of reverse rotation caused by shift of the ,driving plunger over a shoulder of the collar is slightly less than 30 degrees. The driving collar 90 is designed, therefore, for at least approximately 30 degrees of lost motion in its driving connection with the hub member 18. v

The inner configuration of the driving collar 90 provides two diametrically opposite concentrically inner curved walls 92 for rotary engagement with the hub member 18 and provides two diametrically oppositel inner abutments 94. The two abutments 94 form shoulder surfaces 95 for simultaneous abutment against the two side faces 62 of the hub member 18 for imparting clockwise rotation to the hub member.

Figure 8 shows the driving plunger 22 in abutment against a driving face 96a of the driving collar 90 for rotating the driving collar in the operation of tightening a nut or the like. When the resistance of the nut to rotation is suicient to overcome the force exerted by the spring 24, the hubl member 18 and the collar 90 are immobilized and continued manipulation of the wrench causes the driving plunger 22 to ride upon the shoulder 98 that is formed by the face 96a and the next adjacent face 96b. Figure 8a shows this position of the driving plunger 22. When the driving plunger continues to a past center position relative to the shoulder 98, the driving collar 90 rotates backwards or counter-clockwise with a snap action to the position shown in Figure 8b. Since there is freedom for rotation of the driving collar 90 relative to the hub member 18 over this range of reverse movement, the reverse movement does not result in the transmission of any reverse force to the hub member 18. Y

Figures 9 to 10b indicate how a driving collar 100 of octagonal peripheral configuration may be used with the hub member 18. Since the driving collar has eight driving faces, yeach driving face corresponds to 45 degrees of rotation and therefore there should be provision for latl least approximately 221/2 degrees of lost motion between the driving collar and the hub member 18.

Figure 10 shows the driving plunger 22 in abutment with a driving face 102a of the collar 100 in the course of the operation of tightening a nut or the like. When the torque resistance of the nut exceeds the strength of the spring 24 with the parts in the positions shown in Figure l0, the driving collar and the hub member 18 stop rotating and the driving plunger 22 shifts onto the shoulder 103 between the driving face 102a and the; driving face 102b, as shown in Figure 10a. During thisl time the two abutments 104 inside the driving collar 100 are in contact with the side faces 62 of the hub member 18. When the driving plunger 22 shifts clock-A wise slightly beyond the on center position shown in Figure 10a, the driving plunger transmits reverse rotational'- force to snap the driving collar 100 to the position shown in Figure 10b where the driving plunger presses against the second driving face 102b. By virtue of the lost mo* tion provided between the driving collar 100' andtheaalaes..

hubmember 18 no reverse rotational forceisltransmitted: to the hub collar4 by this reversemovement of thefdrivingV collar.

' My description in specicdetail of the selected practiees of the invention will suggest various changes, substitutions and other departures from my disclosure withinzthe spirit and scope of the appended claims.

I claim:

l. In a predetermined torque release wrench, the combination of: ahollowbody; a work-engaging` member rotatably mounted in said body; a driving member operatively connected with said work-engaging member with a range of lost motion in the connection, said driving member= having atleast two successive peripheral driving faces detiningan intervening shoulder; a pressure member positionedfadjacent said driving member for pressure abutnient` against said faces successively; and spring means irl-engagement with said pressure member to create the pressure against said faces tol rotate said driving member againstl torque loads below a given magnitude when said body is turnedy about the axis of the driving member, said spring means yielding to higher torque loads to permit said pressure member to slide over said shoulder froml oneof said faces to the next face with consequent reverse rotational eiect against said next face, said range of lost motion being of a magnitude to accommodate said reverse:V etect thereby. to prevent;V thereverse effect from being transmitted to said work-engaging member.

2L In a predetermined torque 'release wrench, the combination of; a hollow body shaped to serve as a handle; a'work-engaging member rotatably mounted in said body; al hubkmember rotatably mounted in said body; unidirectional clutch means operatively connecting said hub member with said work-engaging member whereby oscillation of the hub member relative to the work-engaging member imparts unidirectional rotation thereto, said hub member being of noncircular cross-sectional configuration; a driving member connected with said hub member withfa range of lost motion in the connection, said driving'4 member having at least two adjacent faces with a shoulder between the twol faces; a pressure member positioned radially of said driving member for abutment against one of said faces; and spring means pressing said pressure member against one of said faces to rotate said driving member against torque loads below a given magnitude when said body is oscillated about the axis oi the driving member, said spring means yielding to` torque loads above said magnitude to permit said pressure member tovslide over Vsaid shoulder to the other of said` faces with consequent reverse rotational elect against said` other. face, said range of lost motion being of a magnitude to accommodate saidreverse elect,thereby toprevent. the reverse eiilectv from being* transmitted to said 111i .m'mber- Y 'A 3f, A combination as set forth in claim 2j in which said driving member is in ratchetengagementwith saidwork-Y engaging member. i

4, .lnna predetermined to-rquerelease wrench, the cornbination` of; a hollow body; a work-engaging member rotatably mounted in said body; a hub member of noncircular cross-sectional conguration operatively connected with said work-engaging member; a 'driving *collar embracing said hub, said driving collar havinga plu-Y rality of succesive.siderfac'es; a pressure memberl in said body positioned adjacent said driving collar lfor 'abutmentagainst a side face thereof; and spring means pressing said pressure member against said collar whereby said pressure member holds said collar against rotation relative tosaid body when said body is rotated about the. axis of the collar against torque loads below a predetermined magnitudeVY and the pressure member yieldingly'retracts to permit said body to rotatel relative to the driving collar when the torque load rises above said magnitude, said pressure member exerting reverse rofst-ivnatfs'rs Qa signaller Ot a, sites. agallas extent as. the. Pressure member Passes, fram. ons. Side face, af. the sellar; i0 the. next Side, face, when Said masaitudsgf; torque loadY isY exceeded, Said. driving 9011er, havingY a. no9il`ular1tral Coatsutaten fer, engaging Said. 140s: circular shankrmeauswith. arotary range* o'flostmction atleast approximatelyy equal to said givenangular extent toprevent said reverse rotational force from beingtransmitted t to said work-engaging member.

5. A combination as set' forth inv claim 4 in which the cross-sectional configuration of: said collar is a polygon having N number of equal sides and saidvrange of lost motion is not substantially less than nor substantially more thanl 6. A combination as set forth in claim 2 in which the peripheral configuration of said collar is square.

7,. A combination as sety forth in` claim 4 in which the peripheral coniiguration of said collar in a hexagon.

8. A` combination as set forth in claim 4` in which the peripheral conligurationof said collar is an Octagon.

9."A lcombination as setlforth in claim 4 in which the cross-sectional coniiguration o f said hub membery is elongated with two parallel sides and in which theinternalfconiguraticn of said driving collar provides at least one internal abutment for engagement with one of said sides.

10. A combination as setr forthkin claim 9 in which the internal configuration of said collar provides two diametrically opposite abutments for engagement with said parallelsides respectively of the hub member.

11.*ln a predetermined torque release wrench, the combination of: alhollowV body having a head portion and havingv a shank portion to. serve as a handle; a workengaging member mounted in said head'porton for rotation` about an axis extending transversely of said shank portion, said work-engagingy member being movable axially in said head portion and having ratchet teeth at its 'inner end; a hub member rotatably mounted in said head portion coaxially of said work-engaging member and formed with ratchet teeth in engagement with the ratchet teeth of said work-engaging member, said hub member being of v non-circular cross-sectional` conguration; springl means urging one of said members axially intoratchetfengagement withtherother o f said members whereby oscillation of said hub member relative toA the work-engaging member imparts unidirectional rotation thereto; a driving collar embracing saidhub member, said drivagfcollr. havingL a plurality, of., SucsSSii/e, Peripheral fases.; driving plunger Positioned. in sadhank prtign radially of saidl driving collar for abutment against aside facel thereof; and spring means pressing saidA plunger against said collar whereby said plunger holds said collar against rotation relative to said body when the body is rotated about the axis of the` collar against torqueleads belgw. a predetermined magnitude and. the plunger. yieldingly retracts to permit thebody to rotate r'elativeto the driving collar when the torque load rises` above said magnitude, said plunger exerting a reversenrotational force on saidcollar of a given angular extent as the plunger passes from one side face of the collar to the next side face when saidi magnitude. of torque load is exceeded, saiddriving collar having a noncircular internal conigurationfor engagingv s aid noncircular hub member with a rotary range 'of lost motion at least approximately equal to said given angular extent toprevent said reverse rotational force from being transmitted.' to said work-engaging member.

@assesses 0a allowing passt.

Referencs Cited in the file of this patent UNITED STATES PATENTS Wood Nov. 8, 1938 Liverrnont Apr. 11, 1950 Mayer June 17, 1952 Garwood July 1, 1952 10 I, Noell Oct. 30, 1956 Woods Mar. 11, 1958 FOREIGN PATENTS Great Britain Sept. 16, 1953 'France Feb. 25, 1953 

